Replies

1. 
   Sphere | Dec 20, 2003 12:08am | #1

   What kind of ''JOINT" an outside corner, scarf, inside corner? Either way get a chop saw, thats what they excel at.

1. 
   fretmaster | Dec 20, 2003 12:16am | #2

   Outside corner joints are what I need to cut.

1. 
   BG | Dec 20, 2003 12:58am | #5

   Freddie,

   I cannot help much but I think you recognize that while your cutting a 45 degree angle...the molding slopes out from the wall and therefore a compound cut is required.  There are tables of numbers that come with the compound miter saws that give the settings.  There was also an article in FWW for making compound cuts with out the numbers about a year ago...it featured a methodology from NBennet St. School.  If you could find the article ( it may be here in the archives) you might be able to futz a solution. 

   The key to their solution was taking a piece of solid stock (in your case probably 4x4)  and cutting the slope you want to replicate ...then they adjusted the miter and blade tilt against the solid stock ...replaced solid stock with work material and cut away...   it did work with a 10 degree slope or flair on some trays I made...  The question is what is the slope of your crown molding?

   I know this doesn't help much...   

2. 
   Steinmetz | Dec 20, 2003 12:30am | #3

   Freddy,if you add a length of 1x4 to your miter gauge high enough to sit higher than the crown mold and long enough to prevent slippage, you can cut both inside and outside cuts on your table saw. set to 45 on  miter gauge and 90 deg's on blade blade.

     I have two miter gauges that are set up 1 LH and 1 RH (Dedicated.)

   Once they are set up to exactly 45, don't touch the adjust ment. I also add a small stop ledge along the 1x4's to keep the moulding from rising. Sandpaper glued to the miter fence also prevents slippage. 

    One note:  Stock crown has a top and bottom facet So, as not to screw up, mark along the tops with a magic marker Stein

   
   

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   Edited 12/19/2003 4:33:11 PM ET by steinmetz

   
   

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   Edited 12/19/2003 8:09:02 PM ET by steinmetz

1. 
   Sphere | Dec 20, 2003 12:50am | #4

   Stein, would he not leave the blade at 90 and just angle the m.gauge? The moulding should be upside down and at the spring angle. and for a left out side miter cut the rt. side of the stock?

   A 45 on both the blade and the moulding spring and the miter ga. wont work.

   I was gonna explain it to him, but felt it would be better for a chop saw..sliding a (could be) long or wide crown over a t.s. is NOT the most accurate or efficient way to go..I am thinking that you may have meant to have the crown verticle against the m. ga. backer board and not at the spring angle..if the sping angle is not truly 45, even if it is..it is much better to present it to the blade sprung..if it is homemade..I hope he has enough to practice with. and that his profile is exact from on end to the other. well we will hear one way or tother..Duane

1. 
   fretmaster | Dec 20, 2003 01:00am | #6

   The crown is homemade and it's about 8 inches in width.. too high to cut on by doing it upside down with the blade at 90 and the miter gauge at 45... is there another way?

   Thanks,

   fred

1. 
   Sphere | Dec 20, 2003 01:22am | #7

   Yup..gotta dig up the tables..that big at 45* hmm...I see problems in your future...If you are certain of the spring at 45 I'll try to find the angles..but it might be faster to just start cutting test parts, esp. if yer wall aint 90..whole new ball o wax..

   try this..www.woodbin.com..if ya have excel, freebie table download..

   Edited 12/19/2003 5:38:08 PM ET by SPHERE

1. 
   fretmaster | Dec 20, 2003 01:43am | #8

   Thanks.. I'll check it out.

   Fred

2. 
   Steinmetz | Dec 20, 2003 04:06am | #14

   Sphere, you are correct. My goof!  After posting, I realized my mistake.  I re- thought my method and wondered how I could have cut the 90deg off cuts without changing the blade's angle. Stein.

1. 
   Sphere | Dec 20, 2003 04:12am | #15

   awl hell, like I've never done that..as an aside..if it were me, I would have used a built up of moldings..if he gets the miter looking sweet, it will not stay that way, unless we are in a perfect world..lol

1. 
   Tao | Dec 20, 2003 04:38am | #18

   >>I would have used a built up of moldings..if he gets the miter looking sweet, it will not stay that way, unless we are in a perfect world..lol

   Good point!  I'm not a trim carpenter, but I do a lot of on-site finishing, and most of the big, wide crown moldings and mantels I have seen, new or old, are built- up.

    Seasonal movement on an 8" molding could possibly be just short of 1/8", and the joints would gap badly at least part of the year, no matter how well fit.

   Michael R.

3. 
   stevemorris | Dec 20, 2003 01:46am | #9

   if you're crown sits at 45 degrees to its flat back, bevel it at 34 and miter at 31.5 with the flat back on the table

   you may have to play around with the angles a little to get a good fit

   most miter saws have these angles marked and better ones have detents for them

   caulking is not a piece of trim

1. 
   Dave10 | Dec 20, 2003 06:35am | #20

   While caulking may not be the most desirable way to finish an installation, it amy be the only way to make-up for sloppy drywalling and still make some money.

4. 
   SgianDubh | Dec 20, 2003 02:19am | #10

   The dihedral angle described between your two pieces is 120º, and the true angle of the side’s shape as it springs from the wall (or from the ceiling [which applies only because 45º is common whether you spring from the ceiling, or from the wall]) is 54.74º

   Therefore to mitre the joint, you need to tilt the sawblade to do a bevel cut of half of 120º, = 60º, and set the mitre gauge to cut both approaches to ~35º, which is 90º minus 55º-- close to 54.74º. This should be right, but it’s not unknown for me to make an almighty cock-up with calculating the necessary cut angles from the data supplied by questioners in this forum, ha, ha.

   Depending on how your gauges read on your table saw, these figures will—nay-- should be correct for a cornice moulding springing from the wall at 45º as you describe, and assumes that your room corner is actually 90º.

   Any variation from the wall/ceiling/corner angles will result in adjusting the cuts that have to be made—and I’ve never yet seen a square corner in a house so there will almost certainly be some adjustment necessary around the figures I’ve provided.

   I’m not aware that there’s any simple formula(e) or charts that will calculate or accommodate all the variables that might occur in constructing polyhedra (and similar things like joining crown mouldings at the corners) but there are charts available on the web that give you figures or saw settings for common polyhedra/hopper type shapes of 4—6—8 sides, etc..

   One resource worth a visit to help explain the arithmetic, and to outline the saw settings necessary is Joe Fusco’s website where he describes the process of cutting crown moulding very well. Do a Google or similar search for Jo(e) Fusco, builder, or carpenter and you should find it easily enough. Slainte.

   Website

1. 
   Elcoholic | Dec 20, 2003 02:54am | #11

   What if he made an L shaped jig to attach to the mitre gauge out of 1x6 say 24" long.  The base would have a ledger tacked to it to support the leading bottom edge of the molding at it's 45* slope from vertical.  Then setting the mitre gauge to 45* would put the saw blade @ 0* tilt in the correct plane for a 90* corner.  This would be the same approach as using a non-compound chop saw would it not?John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   Steinmetz | Dec 20, 2003 03:55am | #13

   Elco, Just what I did; Ledger stip to hold crown up right at the angle required. BUT! my crown was not as wide as eight inches.

   THAT would require a flat down set up as the ten inch blade could never do the job. I think as long as his crown is so wide, and it's not factory made, he should make himself a miter box

    As far as non 90 deg. corners are concerned, a small 'Shim' in the miterbox can shift the cut a 'Smooch'  Stein.

   I neglected to say the Blade is at 90Deg's and the miter cut only is 45. I'm gonna edit that right now.Ed.

   Edited 12/19/2003 8:00:27 PM ET by steinmetz

2. 
   SgianDubh | Dec 20, 2003 11:25am | #21

   John, you are correct. It's usually easier to just 'spring' the moulding at the appropriate 45º angle (in this case) into something like a wooden U shaped channel or L shaped jig with a ledger strip that is rigged up on a chop saw of some sort. In use you simply adjust the mitre gauge to the appropriate 45º angle depending on if it's an inside or outside corner, or if it's the left or right approaching piece to that corner.

   However, I'm pretty sure  freddie has described a piece of moulding where the back flat face forms two corners of a right triangle at 45º where the third corner is 90º. With a hypotenuse of ~8" the two short legs of the triangle formed must be about 5.66" long. Add to this the thickness of the material used for the U or L shaped holding jig, say ~0.75" and it looks like he'd need a depth of cut available of about 6.45" which would suggest spinning something in the region of  an 18" diameter blade in a table saw.

   As others have noted the only way most people could approach this with a U or L shaped springing jig would be to get out a panel saw and go to it by hand, ha, ha. The only other alternative is to tilt both the saw blade and adjust the mitre gauge for each cut at the angles I suggested earlier and lay the piece of moulding flat on the saw table. As I said before, I may have made a cock up on the sums because I only did them once and didn't double or treble check them, ha, ha.

   I see no-one has gone to find Joe Fusco's extremely useful site on this topic and put it up as a link, so I'll just post this and come back with an edit to provide the link. Slainte. 

     Website

1. 
   eddiefromAustralia | Dec 20, 2003 11:59am | #22

   Hi Richard,

   Here tis:

   http://www.josephfusco.org/Articles/Crown_Moulding/crownscript.html

   Hope all's going well with the move/settling in.

   eddie

1. 
   SgianDubh | Dec 20, 2003 12:14pm | #23

   Yep, that's it eddie. Thanks. I'm starting to settle in pretty well. Looking forward to the break at Christmas, and a wee trip up to Edinburgh for a week of debauchery over the Hogmanay period, ha, ha--- ha, ha, ha.

   Anyway, I found the same links, and a description of cutting a huge exterior crown moulding which looks fun, so here they all are, and I think the links will work. I'll see in a minute after I've posted. Slainte.

   http://www.josephfusco.org/Articles/Crown_Moulding/crownscript.html

   http://www.josephfusco.org/Articles/Crown_Moulding/CrownChart.html

   http://www.garymkatz.com/TrimTechniques/cuttinghugecrown.htm

   <a href="http://www.josephfusco.org/Articles/Crown_Moulding/crownscript.html&quot; Website

2. 
   Elcoholic | Dec 21, 2003 07:33am | #24

   Doh!  I was thinking about the geometry not the size of the crown.  Now that it is Saturday night and I've a Newcastle under my belt and several other brave 12 oz. soldiers lined up in the fridge up to face their ultimate destiny it's all clear to me.  And oh yeah I read your and at least one other post that pointed to the size of the blade.  Ever see that 30" (?, but huge by any sane standards) Makita sidewinder saw for trimming rafters and beam ends?  Maybe with the right jigs it'd do the trick.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   SgianDubh | Dec 21, 2003 04:23pm | #25

   No biggie, John. I screw up my maths and miss out bits all the time when posting in forums, and need putting right from time to time. I sometimes fail to double check my information prior to posting. I suppose it's because a real job doesn't depend on getting it just right, ha, ha.

   Nah, never seen one of those big Makita deals in action, but I'd guess if one is rigged up right it would cut big crown moulding easily enough--- but then a hand powered cross cut saw will do the job here pretty well too, and might be a bit cheaper to buy. It might be interesting to see one of those big Makita's going, like one of the 12"+ wide hand held beam planers from (I think) Mafell. Slainte.Website

2. 
   Elcoholic | Dec 22, 2003 06:49am | #27

   I've never seen one in action either.  I've seen them at rental yards, which brings up a pretty scary thought.  Any idiot can just walk up and rent one.  If that thing kicks back it could cut a torso in half.  I think I'd opt to seen either one of these tools operated from a safe distance.  I exaggerated it's only a mere 16 5/16".

   John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

3. 
   Sphere | Dec 21, 2003 06:40pm | #26

   I used a 20" Tannewitz table saw in of all places a Guitar Shop. We laminated billets of maple and morado for thru neck bass's the billets were on the order of 5" x 5" x 60 " ...the 5 hp. Tannewitz once caught a guy off guard and a billet kicked back..drove the rivet from his levis right into his pelvis. Thats after it passed thru his longjohns and his BVD's..ouch.

   THAT was a saw!

5. 
   coonass | Dec 20, 2003 03:46am | #12

   Freddie,

   You could make a wooden miter box and cut with a hand saw. I'd have it made and cut before you adjusted your table saw.

   KK

1. 
   Tao | Dec 20, 2003 04:27am | #17

   >>You could make a wooden miter box and cut with a hand saw. I'd have it made and cut before you adjusted your table saw.

   I could probaly figure this out if I weren't so tired and lazy, but how would you build and cut a miter box big enough to cut an 8" wide molding, even if it were reclining at a 45 degree angle? I figure the depth of cut at just under 6".  Would you just lay out the guide cuts with a square or protractor and cut them withe a handsaw?

   Looks like you'd have to  use a regular crosscut to cut the molding, too.  None of my backsaws, including my two-foot miter saw will cut more than about 4".

   Michael R

1. 
   coonass | Dec 20, 2003 05:49am | #19

   6" wide by 6" high box, angle set with framing square, nice crosscut hand saw or my choice would be Japanese saw. Molding sits upside down just like chopbox. Learned to do it this way a long time ago. All the old houses were done like this.

   KK

6. 
   Steinmetz | Dec 20, 2003 04:15am | #16

   Fred, Re read my post, as I corrected a big goof on my part

   Blade at 90 miter gauge at 45

   Position the molding against the miter gauge at the correct angle and add ledger strip to prevent slip.

   Assume you are on the ceiling and looking down at the joints with the marked facet up.

   If you  had mentioned your crown was 8" wide, I would have

   suggested a miter box.  The subsequent posters have better ideas and suggestions.  Sorry about that, Stein. 

   
   

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   Edited 12/19/2003 8:25:07 PM ET by steinmetz